Electrolytic capacitor

ABSTRACT

The electrolytic capacitor includes two chemically processed anode foils, two cathode foils, four separator sheets, four lead tab terminals, two anode leads and two cathode leads. The two chemically processed anode foils, two cathode foils and four separator sheets are arranged alternately and rolled, to form a capacitor element. Two lead tab terminals are connected to the two chemically processed anode foils, respectively, and the remaining two lead tab terminals are connected to two cathode foils, respectively. The two anode leads are connected to two lead tab terminals, respectively, and the two cathode leads are connected to two lead tab terminals, respectively. As a result, equivalent series resistance can stably be reduced.

This application is a continuation application of U.S. application Ser.No. 11/600,781 filed on Nov. 17, 2006. The priority applications NumbersJP2005-337413 and JP2006-231567 of the above parent application arehereby incorporated by reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to an electrolytic capacitor allowingreduction of equivalent series resistance.

2. Description of the Background Art

Recently, there have been demands for electric circuits that are smallerin size and adapted for high-frequency applications. With this trend,capacitors of lower impedance become necessary. Particularly, indesigning a circuit for driving a CPU (Central Processing unit) of acomputer, a switching power supply circuit and the like, absorption ofhigh-frequency noise and ripple current is necessary, and therefore, acapacitor of which equivalent series resistance (ESR) can be made lowhas been required.

FIG. 27 is a perspective view showing a structure of a conventionalaluminum-rolled solid electrolytic capacitor. Referring to FIG. 27, theconventional aluminum-rolled solid electrolytic capacitor 100 includes achemically processed anode foil 110, a cathode foil 120, a separatorsheet 130, a securing tape 140, lead tab terminals 160, 170, an anodelead 180 and a cathode lead 190.

Chemically processed anode foil 110, cathode foil 120 and separatorsheet 130 are rolled such that separator sheet 130 is positioned betweenchemically processed anode foil 110 and cathode foil 120. Securing tape140 tapes ends of the rolled chemically processed anode foil 110,cathode foil 120 and separator sheet 130, and thus, a capacitor element150 is formed.

Lead tab terminal 160 is connected to chemically processed anode foil110 to protrude from an end surface of capacitor element 150, while leadtab terminal 170 is connected to cathode foil 120 to protrude from theend surface of capacitor element 150. Anode lead 180 is connected tolead tab terminal 160 and cathode lead 190 is connected to lead tabterminal 170.

Conventionally, as a method of reducing equivalent series resistance,connecting two leads to each of the chemically processed anode foil andcathode foil has been known (Japanese Patent Laying-Open No.2004-179621). FIG. 28 shows a method of connecting two anode leads tothe chemically processed anode foil. Referring to FIG. 28, two lead tabterminals 160 a and 160 b are connected, spaced by a prescribed distancefrom each other, to chemically processed anode foil 110. Two anode leads180 a and 180 b are respectively connected to lead tab terminals 160 aand 160 b.

Two cathode leads are connected to cathode foil 120 in the similarmanner as two anode leads 180 a and 180 b are connected to chemicallyprocessed anode foil 110.

FIG. 29 is another illustration showing a method of connecting two anodeleads to the chemically processed anode foil. Referring to FIG. 29, alead tab terminal 160 c is connected to chemically processed anode foil110, and two anode leads 180 a and 180 b are connected, spaced by aprescribed distance from each other, to lead tab terminal 160 c. Twocathode leads are connected to cathode foil 120 in the similar manner astwo anode leads 180 a and 180 b are connected to chemically processedanode foil 110.

In the conventional aluminum-rolled solid electrolytic capacitor,equivalent series resistance can be reduced to about 2.0 mΩ.

As described above, it has been known that equivalent series resistancecan be reduced by connecting two leads to each of the chemicallyprocessed anode foil and the cathode foil.

According to the conventional method of reducing equivalent seriesresistance, however, a plurality of anode leads are connected to thechemically processed anode foil and a plurality of cathode leads areconnected to the cathode foil, and therefore, it has been difficult tofabricate an aluminum-rolled electrolytic capacitor while maintainingconstant the positions for connecting the plurality of anode leads tothe chemically processed anode foil and the positions for connecting theplurality of cathode leads to the cathode foil.

Consequently, it has been difficult to fabricate an aluminumelectrolytic capacitor with low ESR in a stable manner. Specifically,dependent on the position of connection between the anode lead and thechemically processed anode foil and the position of connection betweenthe cathode lead and the cathode foil, the equivalent series resistancevaries (Japanese Patent Laying-Open No. 2005-203402), and therefore, itis difficult to connect the plurality of anode leads and a plurality ofcathode leads to the chemically processed anode foil and the cathodefoil every time at the same positions to fabricate aluminum electrolyticcapacitors having approximately the same equivalent series resistance.

SUMMARY OF THE INVENTION

The present invention was made to solve these problems, and its objectis to provide an electrolytic capacitor allowing stable reduction ofequivalent series resistance.

According to an aspect, the present invention provides a rolled typeelectrolytic capacitor containing an electrolyte, including i (i is aninteger not smaller than 2) anode members, j (j is an integer satisfying1≦j<i) cathode members, and k (k is an integer not smaller than 2)separator members, wherein i anode members are electrically insulatedfrom each other and each has a dielectric coating film on its surface, jcathode members are rolled together with the i anode members, and kseparator members are arranged between at least i anode members and jcathode members and rolled together with the i anode members and jcathode members.

According to another aspect, the present invention provides a rolledtype electrolytic capacitor containing an electrolyte, including i (i isan integer not smaller than 2) anode members, i cathode members and k (kis an integer not smaller than 2) separator members. Here, i anodemembers are electrically insulated from each other and each has adielectric coating film on its surface, i cathode members are rolledtogether with the i anode members, and i separator members are eacharranged between adjacent anode member and cathode member, and rolledtogether with the i anode members and i cathode members. The diameterwhen i anode members, i cathode members and k separator members arerolled is approximately the same as the diameter of a referenceelectrolytic capacitor formed by rolling one anode member and onecathode member with one or two separator sheets inserted therebetween.

Preferably, the i anode members, the i cathode members and the kseparator members include n (n is an integer not smaller than 2) anodemembers, n cathode members and 2n or 2n−1 separator members. Each of theanode members, cathode members and separator members has approximately1/n the length of the anode member, the cathode member and the separatormember of the reference electrolytic capacitor.

Preferably, the diameter attained when the i anode members, the jcathode members and the k separator members are rolled is approximatelythe same as the diameter of the reference electrolytic capacitor havingone anode member and one cathode member rolled with one or two separatormembers interposed.

Preferably, a capacitor element formed by rolling the n anode members,the n cathode members and the 2n or 2n−1 separator members includes ncapacitors arranged at radially different positions.

Preferably, the i anode members and the j cathode members respectivelyinclude n (n is an integer not smaller than 2) anode members and m (m isan integer satisfying 1≦m<n) cathode members, length of the anode memberis approximately 1/n the length of the anode member in the referenceelectrolytic capacitor, and length of the cathode member isapproximately 1/m the length of the cathode member in the referenceelectrolytic capacitor.

Preferably, a capacitor element formed by rolling the n anode members,the m cathode members and the k separator members includes n capacitorsarranged at radially different positions.

Preferably, the m cathode members include one cathode member.

Preferably, the i anode members, the j cathode members and the kseparator members form a plurality of capacitors having mutuallydifferent capacitances.

Preferably, the electrolytic capacitor further includes a sealingmember. The sealing member seals the capacitor element formed by rollingi anode members, i or j cathode members and k separator members. Thesealing member is formed of resin.

Preferably, the electrolytic capacitor further includes a sealingmember. The sealing member seals the capacitor element formed by rollingi anode members, i or j cathode members and k separator members. Thesealing member is formed of rubber.

Preferably, the electrolytic capacitor further includes i anode leads, jcathode leads, an anode electrode and a cathode electrode. The i anodeleads are provided corresponding to i anode members, and each lead isconnected to approximately the center of the corresponding anode memberin the lengthwise direction of the corresponding anode member. The icathode leads are provided corresponding to the i or j cathode members,and each lead is connected to approximately the center of thecorresponding cathode member in the lengthwise direction of thecorresponding cathode member. The anode terminal is connected to the ianode leads. The cathode terminal is connected to the i cathode leads.The i anode leads have one end connected to i anode members and theother end opposite to the one end connected to the anode terminal. The icathode leads have one end connected to j cathode members and the otherend opposite to the one end connected to the cathode terminal.

Preferably, the electrolyte is solid electrolyte formed ofpolythiophene-group, polypyrrole-group or polyaniline-group conductivepolymer or solid electrolyte of 7, 7, 8, 8-tetracyano-quinodimethane(TCNQ) complex salt.

The electrolytic capacitor in accordance with the present invention isformed by a plurality of anode members and at least one cathode memberarranged alternately and rolled with a separator member interposed. Theelectrolytic capacitor attains the same effect as attained by aplurality of capacitor elements connected in parallel. Specifically, theelectrolytic capacitor has the sum of capacitor capacitance of each ofthe plurality of capacitor elements, and the equivalent seriesresistance is reduced to about the original value divided by the numberof the plurality of capacitor elements.

Therefore, by the present invention, the equivalent series resistance ofthe electrolytic capacitor can be reduced.

The foregoing and other objects, features, aspects and advantages of thepresent invention will become more apparent from the following detaileddescription of the present invention when taken in conjunction with theaccompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view showing a structure of an electrolyticcapacitor in accordance with Embodiment 1 of the present invention.

FIG. 2 is a cross-sectional view showing a structure of the electrolyticcapacitor in accordance with Embodiment 1 of the present invention.

FIG. 3 is a plan view of the electrolytic capacitor viewed from thedirection A of FIG. 2.

FIG. 4 is a plan view illustrating in detail the chemically processedanode foil and the lead tab terminal.

FIG. 5 is a perspective view showing the method of arranging twochemically processed anode foils, two cathode foils and four separatorsheets.

FIG. 6 is an illustration showing a method of rolling the chemicallyprocessed anode foils, the cathode foils and the separator sheets.

FIG. 7 is another illustration showing a method of rolling thechemically processed anode foils, the cathode foils and the separatorsheets.

FIG. 8 is another perspective view showing the structure of theelectrolytic capacitor in accordance with Embodiment 1 of the presentinvention.

FIG. 9 is a plan view of the separator sheet shown in FIG. 8.

FIG. 10 is a perspective view showing a method of arranging thechemically processed anode foils, the cathode foils and the separatorsheets when the electrolytic capacitor shown in FIG. 8 is fabricated.

FIG. 11 is a still another perspective view showing the structure of theelectrolytic capacitor in accordance with Embodiment 1 of the presentinvention.

FIG. 12 is a plan view of the chemically processed anode foils and thecathode foils.

FIG. 13 is a perspective view showing a structure of an electrolyticcapacitor in accordance with Embodiment 2.

FIG. 14 is a plan view of the cathode foil shown in FIG. 13.

FIG. 15 is a perspective view showing the method of arranging thechemically processed anode foils, cathode foil and separator sheets whenthe electrolytic capacitor shown in FIG. 13 is fabricated.

FIG. 16 is a perspective view showing another method of arranging thechemically processed anode foils, cathode foil and separator sheets whenthe electrolytic capacitor shown in FIG. 13 is fabricated by using twochemically processed anode foils and one cathode foil.

FIG. 17 is a perspective view showing a still another method ofarranging the chemically processed anode foils, cathode foil andseparator sheets when the electrolytic capacitor shown in FIG. 13 isfabricated by using two chemically processed anode foils and one cathodefoil.

FIG. 18 is another perspective view showing the structure of theelectrolytic capacitor in accordance with Embodiment 2.

FIG. 19 is a plan view of the chemically processed anode foils, thecathode foil and the separator sheets forming the electrolytic capacitorshown in FIG. 18.

FIG. 20 is a perspective view showing a method of arranging thechemically processed anode foils, cathode foil and separator sheets whenthe electrolytic capacitor shown in FIG. 18 is fabricated.

FIG. 21 is a perspective view showing a method of arranging thechemically processed anode foils, cathode foil and separator sheets whenthe electrolytic capacitor shown in FIG. 18 is fabricated by using threechemically processed anode foils and one cathode foil.

FIG. 22 is a perspective view showing another method of arranging thechemically processed anode foils, cathode foil and separator sheets whenthe electrolytic capacitor shown in FIG. 18 is fabricated by using threechemically processed anode foils and one cathode foil.

FIG. 23 is a still further perspective view showing the structure of theelectrolytic capacitor in accordance with Embodiment 2.

FIG. 24 is a plan view of the chemically processed anode foils, cathodefoils and separator sheets forming the electrolytic capacitor shown inFIG. 23.

FIG. 25 is a perspective view showing a method of arranging thechemically processed anode foils, cathode foils and separator sheetswhen the electrolytic capacitor shown in FIG. 23 is fabricated.

FIG. 26 is a perspective view showing a method of arranging thechemically processed anode foils, cathode foils and separator sheetswhen the electrolytic capacitor shown in FIG. 23 is fabricated by usingthree chemically processed anode foils and two cathode foils.

FIG. 27 is a perspective view showing a structure of a conventionalaluminum rolled solid electrolytic capacitor.

FIG. 28 is an illustration showing a method of connecting two anodeleads and the chemically processed anode foil.

FIG. 29 is another illustration showing a method of connecting two anodeleads and the chemically processed anode foil.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

Embodiments of the present invention will be described in detail withreference to the figures. Throughout the figures, the same orcorresponding portions are denoted by the same reference characters anddescription thereof will not be repeated.

Embodiment 1

FIG. 1 is a perspective view showing a structure of an electrolyticcapacitor in accordance with Embodiment 1 of the present invention. FIG.2 is a cross-sectional view showing a structure of the electrolyticcapacitor in accordance with Embodiment 1 of the present invention.Referring to FIGS. 1 and 2, an electrolytic capacitor 10 in accordancewith Embodiment 1 of the present invention includes a chemicallyprocessed anode foil 1, a cathode foil 2, a separator sheet 3, asecuring tape 4, lead tab terminals 6 to 9, anode leads 11, 12, cathodeleads 13, 14, a case 15, a rubber packing 16, and a seat plate 17.

Electrolytic capacitor 10 is, by way of example, an electrolyticcapacitor including solid electrolyte.

Chemically processed anode foil 1 includes two chemically processedanode foils 1 a and 1 b. Each of the two chemically processed anodefoils 1 a and 1 b is formed of aluminum foil with its surface chemicallyprocessed. Therefore, each of the two chemically processed anode foils 1a and 1 b has its surface made rough and has an oxide film formed on theroughened surface.

Cathode foil 2 includes two cathode foils 2 a and 2 b. Each of the twocathode foils 2 a and 2 b is formed of aluminum foil. Separator sheet 3includes four separator sheets 3 a to 3 d.

Separator sheet 3 a, chemically processed anode foil 1 a, separatorsheet 3 b, cathode foil 2 a, separator sheet 3 c, chemically processedanode foil 1 b, separator sheet 3 d and cathode foil 2 b are arrangedsuccessively, and the arranged separator sheet 3 a, chemically processedanode foil 1 a, separator sheet 3 b, cathode foil 2 a, separator sheet 3c, chemically processed anode foil 1 b, separator sheet 3 d and cathodefoil 2 b are rolled. Then, ends of the rolled separator sheet 3 a,chemically processed anode foil 1 a, separator sheet 3 b, cathode foil 2a, separator sheet 3 c, chemically processed anode foil 1 b, separatorsheet 3 d and cathode foil 2 b are secured by securing tape 4. In thismanner, a capacitor element 5 is formed.

In capacitor element 5, chemically processed anode foil 1 a, separatorsheet 3 b and cathode foil 2 a form one capacitor element 5 a, whilechemically processed anode foil 1 b, separator sheet 3 d and cathodefoil 2 b form one capacitor element 5 b.

Lead tab terminal 6 is connected to chemically processed anode foil 1 a,and lead tab terminal 7 is connected to chemically processed anode foil1 b. Further, lead tab terminal 8 is connected to cathode foil 2 a, andlead tab terminal 9 is connected to cathode foil 2 b.

Anode leads 11 and 12 are connected to lead tab terminals 6 and 7,respectively, and cathode leads 13 and 14 are connected to lead tabterminals 8 and 9, respectively.

Case 15 is formed of aluminum, and houses capacitor element 5, lead tabterminals 6 to 9, anode leads 11 and 12 and cathode leads 13 and 14.Rubber packing 16 seals capacitor element 5 and lead tab terminals 6 to9 in case 15. Seat plate 17 fixes anode leads 11 and 12 as well ascathode leads 13 and 14. Anode leads 11 and 12 and cathode leads 13 and14 are bent along seat plate 17 when capacitor element 5 is put in case15.

FIG. 3 is a plan view of electrolytic capacitor 10 viewed from thedirection A of FIG. 2. Referring to FIG. 3, seat plate 17 has anapproximately rectangular planar shape, and has cut outs 17A to 17D.Anode leads 11 and 12 and cathode leads 13 and 14 are bent to the innerside of seat plate 17 to be fit in cut outs 17A to 17D of seat plate 17.

The bent two anode leads 11 and 12 and two cathode leads 13 and 14 areused as terminals of electrolytic capacitor 10. Therefore, electrolyticcapacitor 10 is an electrolytic capacitor having a 4-terminal structure.

FIG. 4 is a plan view illustrating in detail chemically processed anodefoil 1 a and lead tab terminal 6. Referring to FIG. 4, chemically formedanode film 1 a has a rectangular planar shape, of which length L isone-half the length 2L of a conventional chemically processed anode foil110 and the width W is the same as that of the conventional chemicallyprocessed anode foil 110.

Lead tab terminal 6 is connected to chemically formed cathode foil 1 aat a position of L/2 from a rolling start end 1A of chemically processedanode foil 1 a. In this manner, lead tab terminal 6 is connected at thecentral portion of chemically processed anode foil 1 a along thelengthwise direction of chemically processed anode foil 1 a.

Chemically processed anode foil 1 b and each of cathode foils 2 a and 2b have the same length L and the same width W as chemically processedanode foil 1 a. Lead tab terminals 7 to 9 are respectively connected tothe central portion of chemically processed anode foil 1 b and cathodefoils 2 a and 2 b.

Separator sheet 3 (3 a˜3 d) is longer than chemically processed anodefoil 1 and cathode foil 2, and wider than chemically processed anodefoil 1 and cathode foil 2. This is to prevent short-circuit betweenchemically processed anode foil 1 and cathode foil 2.

As described above, chemically processed anode foil 1 and cathode foil 2have the length L, which is half the length 2L of conventionalchemically processed anode foil 110, and the width W, which is the sameas that of conventional chemically processed anode foil 110. Therefore,the area S of each of chemically processed anode foil 1 and cathode foil2 becomes one-half the area S0 of conventional chemically processedanode foil 110. As a result, capacitance C of each of capacitor elements5 a and 5 b becomes one-half the capacitance C0 of a capacitor elementformed by using chemically processed anode foil 110.

Capacitor element 5, however, has the same effect as attained by twocapacitor elements 5 a and 5 b having the capacitance C connected inparallel, and therefore, the resulting capacitance becomes 2C (=C0).Namely, it is the same as the capacitance C0 of conventional aluminumrolled solid electrolytic capacitor 100 formed by rolling one chemicallyprocessed anode foil 110 and one cathode foil 120 with one separatorsheet 130 interposed.

Therefore, even though electrolytic capacitor 10 is fabricated by usingchemically processed anode foil 1 and cathode foil 2 having one-half thelength of conventional chemically processed anode foil 110, itscapacitance is not smaller than that of conventional aluminum rolledsolid electrolytic capacitor 100.

Further, electrolytic capacitor 10 is fabricated by rolling chemicallyprocessed anode foil 1 and cathode foil 2 having one-half the length ofconventional chemically processed anode foil 110, the diameter afterrolling is approximately the same as the conventional aluminum rolledsolid electrolytic capacitor 100. In other words, it becomes possible tofabricate electrolytic capacitor 10 while maintaining the capacitanceand not enlarging the size from that of conventional aluminum rolledsolid electrolytic capacitor 100.

The method of fabricating electrolytic capacitor 10 will be described.FIG. 5 is a perspective view showing the method of arranging twochemically processed anode foils 1 a and 1 b, two cathode foils 2 a and2 b, and four separator sheets 3 a to 3 d. FIG. 6 is an illustrationshowing a method of rolling chemically processed anode foils 1 a and 1b, cathode foils 2 a and 2 b, and separator sheets 3 a to 3 d. First, asurface of large aluminum foil is etched and then chemically processed.The chemically processed aluminum foil is cut, to provide two aluminumfoils having a prescribed dimension (length L and width W), and thus twochemically processed anode foils 1 a and 1 b are formed.

Next, by the similar method as forming chemically processed anode foils1 a and 1 b, two cathode foils 2 a, 2 b having the prescribed dimension(length L and width W) are fabricated. Further, four separator sheets ofa prescribed dimension (length L+α, width W+α) are cut, as separatorsheets 3 a to 3 d.

Thereafter, anode leads 11 and 12 are respectively connected to lead tabterminals 6 and 7, and cathode leads 13 and 14 are respectivelyconnected to lead tab terminals 8 and 9. Then, lead tab terminals 6 and7 are connected to the central portion of chemically processed anodefoils 1 a and 1 b, respectively, and lead tab terminals 8 and 9 areconnected to the central portion of cathode foils 2 a and 2 b,respectively.

Thereafter, the two chemically processed anode foils 1 a and 1 b, twocathode foils 2 a and 2 b and four separator sheets 3 a to 3 d arearranged in the manner as shown in FIG. 5 and rolled. Specifically, twochemically processed anode foils 1 a and 1 b, two cathode foils 2 a and2 b and four separator sheets 3 a to 3 d are arranged such that rollingstart ends of two chemically processed anode foils 1 a and 1 b, twocathode foils 2 a and 2 b and four separator sheets 3 a to 3 d arealigned, and two chemically processed anode foils 1 a and 1 b, twocathode foils 2 a and 2 b and four separator sheets 3 a to 3 d arerolled. More specifically, two chemically processed anode foils 1 a and1 b, two cathode foils 2 a and 2 b and four separator sheets 3 a to 3 dare arranged in the manner as shown in FIG. 6, and two chemicallyprocessed anode foils 1 a and 1 b, two cathode foils 2 a and 2 b andfour separator sheets 3 a to 3 d are rotated clockwise (orcounterclockwise) about a fulcrum FLC, so that two chemically processedanode foils 1 a and 1 b, two cathode foils 2 a and 2 b and fourseparator sheets 3 a to 3 d are rolled. Thus, capacitor element 5 isfabricated. It is noted that two chemically processed anode foils 1 aand 1 b, two cathode foils 2 a and 2 b and four separator sheets 3 a to3 d may be rolled with the rolling start ends of two chemicallyprocessed anode foils 1 a and 1 b, two cathode foils 2 a and 2 b andfour separator sheets 3 a to 3 d not aligned.

Thereafter, capacitor element 5 having lead tab terminals 6 to 9, anodeleads 11 and 12, and cathode leads 13 and 14 connected thereto issubjected to cut-edge chemical processing and heat treatment at 150° C.to 300° C., and capacitor element 5 is impregnated with a mixture. Themixture contains a monomer that will be a conductive polymer throughpolymerization, and an alcoholic solution of ferric p-toluene sulfonicacid as an oxidizer solution.

Then, by thermochemical polymerization, a layer of conductive polymer isformed between two electrodes of capacitor element 5. Consequently,capacitor element 5 comes to include an electrolyte. The electrolyte is,by way of example, polythiophene-group, polypyrrole-group orpolyaniline-group conductive polymer or solid electrolyte of 7, 7, 8,8-tetracyano-quinodimethane (TCNQ) complex salt. After impregnation ofcapacitor element 5 with the electrolyte, rubber packing 16 is insertedto capacitor element 5, and capacitor element 5 having rubber packing 16inserted is put and fixed in case 15.

Thereafter, an opening of case 15 is laterally drawn and curled to sealrubber packing 16 and capacitor element 5, and aging process isconducted. Thereafter, seat plate 17 is inserted to the curled surfaceof capacitor element 5, and anode leads 11 and 12 and cathode leads 13and 14 as electrode terminals are pressed and bent. Thus, electrolyticcapacitor 10 is completed.

FIG. 7 is another illustration showing a method of rolling chemicallyprocessed anode foils 1 a and 1 b, the cathode foils 2 a and 2 b and theseparator sheets 3 a to 3 d. Electrolytic capacitor 10 may be fabricatedin the following manner. Two chemically processed anode foils 1 a and 1b and two cathode foils 2 a and 2 b are formed in the similar manner asdescribed above.

Thereafter, two separator sheets 3 a and 3 c having the length L+α andwidth W+α, and one separator sheet 3 e having the length 2 L+α and widthW+α are prepared. Then, anode leads 11 and 12 are respectively connectedto lead tab terminals 6 and 7, and cathode leads 13 and 14 arerespectively connected to lead tab terminals 8 and 9. Thereafter, leadtab terminals 6 and 7 are connected respectively to the central portionof chemically formed cathode foils 1 a and 1 b, and lead tab terminals 8and 9 are respectively connected to the central portion of cathode foils2 a and 2 b.

Then, two chemically processed anode foils 1 a and 1 b, two cathodefoils 2 a and 2 b and three separator sheets 3 a, 3 c and 3 e arearranged in the manner as shown in FIG. 6, and two chemically processedanode foils 1 a and 1 b, two cathode foils 2 a and 2 b and threeseparator sheets 3 a, 3 c and 3 e are rotated clockwise (orcounterclockwise) about the fulcrum FLC, so that two chemicallyprocessed anode foils 1 a and 1 b, two cathode foils 2 a and 2 b andthree separator sheets 3 a, 3 c and 3 e are rolled. Thus, capacitorelement 5 is fabricated.

Thereafter, electrolytic capacitor 10 is fabricated by the same methodas described above. When electrolytic capacitor 10 is formed in themanner as shown in FIG. 7, rolled separator sheet 3 e serves asseparator sheets 3 b and 3 d.

Further, according to the present invention, electrolytic capacitor 10may be fabricated in the following manner. The method of fabricationdescribed below is to fabricate electrolytic capacitor 10 by using aroll of aluminum foil having a prescribed width (500 mm). First, asurface of the aluminum foil having the prescribed width (500 mm) isetched and then chemically processed, and two chemically processed anodefoils 1 a and 1 b and two cathode foils 2 a and 2 b are formed.

Thereafter, anode leads 11 and 12 are respectively connected to lead tabterminal 6 and 7, and cathode leads 13 and 14 are respectively connectedto lead tab terminals 8 and 9. Then, lead tab terminals 6 and 7 arerespectively connected to the central portion of chemically processedanode foils 1 a and 1 b, and lead tab terminals 8 and 9 are respectivelyconnected to the central portion of cathode foils 2 a and 2 b.

Then, two chemically formed cathode foils 1 a and 1 b (in a roll) andtwo cathode foils 2 a and 2 b (in a roll) and four separator sheets (ina roll) having a prescribed width W+α are rolled in the manner as shownin FIG. 6 or FIG. 7, and cut in a prescribed length L. Thus, capacitorelement 5 is fabricated.

Thereafter, electrolytic capacitor 10 is fabricated by the same methodas described above.

When electrolytic capacitor 10 is fabricated using two chemicallyprocessed anode foils 1 a and 1 b and two cathode foils 2 a and 2 b inthe manner as described above, four or three separator sheets are used.

Next, electric characteristics of electrolytic capacitor 10 will bedescribed. Table 1 shows, in comparison, electric characteristics ofelectrolytic capacitor 10 in accordance with Embodiment 1 and theconventional electrolytic capacitor.

TABLE 1 Number of electrode Capacitance tanδ ESR Cathode foil foils (μF)(%) (mΩ) Conventional Aluminum foil 1 565 2.5 5.5 Example 1 Example 1Aluminum foil 2 562 2.4 2.8 Example 2 Aluminum foil 3 563 2.5 1.9Conventional Aluminum 1 1520 1.8 7.0 Example 2 nitride film Example 3Aluminum 2 1560 1.8 3.6 nitride film Example 4 Aluminum 3 1530 1.9 2.4nitride film

In Table 1, Conventional Examples 1 and 2 represent electrolyticcapacitors including only one capacitor element 150 fabricated by usingchemically processed anode foil 110 and cathode foil 120 having thelength 2L, while Example 1 represents electrolytic capacitor 10fabricated by using two chemically processed anode foils 1 and twocathode foils 2.

Example 2 represents electrolytic capacitor 10 fabricated by using threechemically processed anode foils 1 and three cathode foils 2, andExample 3 represents electrolytic capacitor 10 fabricated by using twochemically processed anode foils 1 and two cathode foils 2 with cathodefoil 2 replaced by one prepared by forming titanium aluminum nitridefilm on the surface of aluminum foil.

Further, Example 4 represents electrolytic capacitor 10 fabricated byusing three chemically processed anode foils 1 and three cathode foils 2with cathode foil 2 replaced by one prepared by forming titaniumaluminum nitride film on the surface of aluminum foil.

Capacitance and dielectric tangent (tan δ) were measured at 120 Hz, andequivalent series resistance ESR was measured at 100 kHz.

The titanium aluminum nitride film was formed on the surface of aluminumfoil by vapor deposition. Further, in the examples in which the numberof chemically processed anode foils 1 and cathode foils 2 was set tothree, the length of chemically processed anode foil 1 and cathode foil2 was set to one-third of the length 2L of conventional chemicallyprocessed anode foil 110 and cathode foil 120. Further, the values ofcapacitance, dielectric tangent (tan δ) and equivalent series resistanceESR shown in Table 1 are average values of 30 samples.

From the results shown in Table 1, it can be seen that the capacitanceand dielectric tangent (tan δ) of electrolytic capacitor 10 areapproximately the same as those of Conventional Examples 1 and 2. Whenthe number of chemically processed anode foils 1 and cathode foils 2 istwo, equivalent series resistance ESR of electrolytic capacitor 10 inaccordance with the present invention is reduced to about one-half thatof Conventional Examples 1 and 2 (see Examples 1 and 3).

Further, when the number of chemically processed anode foils 1 andcathode foils 2 is three, equivalent series resistance ESR ofelectrolytic capacitor 10 in accordance with the present invention isreduced to about one-third that of Conventional Examples 1 and 2 (seeExamples 2 and 4).

Therefore, when the number of chemically processed anode foils 1 andcathode foils 2 is set to two or three and the length of chemicallyprocessed anode foils 1 and cathode foils 2 is set to one-half orone-third of the length 2L of the conventional chemically processedanode foil 110 and cathode foil 120, it is possible to reduce equivalentseries resistance ESR to about one-half or one-third, while thecapacitance and dielectric tangent of electrolytic capacitor 10 aremaintained.

Specifically, by rolling two or three chemically processed anode foils 1and cathode foils 2 with separator sheets 3 interposed, it becomespossible to fabricate the electrolytic capacitor 10 having the sameeffect as attained by two or three capacitor elements connected inparallel.

In Table 1, Conventional Example 2 and Examples 3 and 4 have largercapacitance than Conventional Example 1 and Examples 1 and 2, becauseconnection between cathode foil 2 and the conductive polymer is improvedby the titanium aluminum nitride film formed on the surface of cathodefoil 2, and hence overall capacitance is increased. Specifically, whenwe represent the capacitor capacitance (electrostatic capacitance) as C,capacitance of the anode foil as Ca and capacitance of the cathode foilas Cc, the capacitor capacitance (electrostatic capacitance) iscalculated as 1/C=1/Ca+1/Cc. When the aluminum nitride film is formed onthe surface of the cathode foil, the capacitance of cathode foil Cc ismaximized (or increased to infinity) and capacitor capacitance(electrostatic capacitance) C comes as close as possible to zero.Therefore, capacitor capacitance (electrostatic capacitance) C attainsC=Ca. As a result, even when the same anode foil is used, the capacitorcapacitance increases.

FIG. 8 is another perspective view showing the structure of theelectrolytic capacitor in accordance with Embodiment 1 of the presentinvention. The electrolytic capacitor in accordance with Embodiment 1 ofthe present invention may be an electrolytic capacitor 10A shown in FIG.8. Referring to FIG. 8, electrolytic capacitor 10A is the same aselectrolytic capacitor 10 except that separator sheets 3 a to 3 d ofelectrolytic capacitor 10 are replaced by separator sheets 3 f and 3 g.

Electrolytic capacitor 10A consists of two capacitor elements 5 c and 5d, formed by rolling two chemically processed anode foils 1 a and 1 b,two cathode foils 2 a and 2 b, and two separator sheets 3 f and 3 g.

Capacitor element 5 c consists of chemically processed anode foil 1 a,cathode foil 2 a and separator sheets 3 f and 3 g, and capacitor element5 d consists of chemically processed anode foil 1 b, cathode foil 2 band separator sheets 3 f and 3 g. Capacitor element 5 c is arranged onthe inner circumferential side, and capacitor element 5 d is arranged onthe outer circumferential side. Therefore, it is the case thatelectrolytic capacitor 10A is formed of two capacitor elements 5 c and 5d arranged at radially different positions.

FIG. 9 is a plan view of separator sheets 3 f and 3 g shown in FIG. 8.Referring to FIG. 9, each of separator sheets 3 f and 3 g has the length2L+α and the width W+α.

FIG. 10 is a perspective view showing a method of arranging chemicallyprocessed anode foils 1 a and 1 b, cathode foils 2 a and 2 b andseparator sheets 3 f and 3 g when electrolytic capacitor 10A shown inFIG. 8 is fabricated. Referring to FIG. 9, two chemically processedanode foils 1 a and 1 b are arranged continuously between separatorsheets 3 f and 3 g. Here, two chemically processed anode foils 1 a and 1b are arranged spaced by a prescribed distance to be electricallyinsulated from each other. Further, cathode foil 2 a is arranged to beopposite to chemically processed anode foil 1 a with separator sheet 3 ginterposed, and cathode foil 2 b is arranged to be opposite tochemically processed anode foil 1 b with separator sheet 3 g interposed.As a result, two cathode foils 2 a and 2 b come to be arrangedcontinuously in the direction of rolling DR1. Here, two cathode foils 2a and 2 b are arranged spaced by a prescribed distance to beelectrically insulated from each other. Thus, in electrolytic capacitor10A, two chemically processed anode foils 1 a and 1 b and two cathodefoils 2 a and 2 b are arranged continuously in the direction of rollingDR1.

By arranging two chemically processed anode foils 1 a and 1 b, twocathode foils 2 a and 2 b and two separator sheets 3 f and 3 g in themanner as shown in FIG. 10, and two chemically processed anode foils 1 aand 1 b, two cathode foils 2 a and 2 b and two separator sheets 3 f and3 g are rolled from rolling start ends 1A, 2A and 3A in the direction ofrolling DR1, so that capacitor element 5 including two capacitorelements 5 c and 5 d is formed. At the point where chemically processedanode foil 1 a, cathode foil 2 a and separator sheets 3 f and 3 g of thelength L are rolled, capacitor element 5 c is formed, and at the pointwhere chemically processed anode foil 1 b, cathode foil 2 b andseparator sheets 3 f and 3 g of the remaining length L are rolled,capacitor element 5 d is formed.

Consequently, it follows that capacitor element 5 c is arranged on theinner circumferential side, and capacitor element 5 d is arranged on theouter circumferential side.

After forming capacitor element 5 by rolling two chemically processedanode foils 1 a and 1 b, two cathode foils 2 a and 2 b and two separatorsheets 3 f and 3 g, electrolytic capacitor 10A is fabricated by the samemethod as that of fabricating electrolytic capacitor 10.

In fabricating electrolytic capacitor 10A, it is unnecessary that twochemically processed anode foils 1 a and 1 b, two cathode foils 2 a and2 b and two separator sheets 3 f and 3 g are rolled from the rollingstart ends 1A, 2A and 3A, and two chemically processed anode foils 1 aand 1 b, two cathode foils 2 a and 2 b and two separator sheets 3 f and3 g may be rolled from the central portion of two separator sheets 3 fand 3 g. Dependent on the manner of rolling two chemically processedanode foils 1 a and 1 b, two cathode foils 2 a and 2 b and two separatorsheets 3 f and 3 g, lead tab terminals 6 to 9 come to be arranged in arectangle as shown in FIG. 1 or arranged linearly as shown in FIG. 8.

Further, in fabricating electrolytic capacitor 10A, two chemicallyprocessed anode foils 1 a and 1 b, two cathode foils 2 a and 2 b and twoseparator sheets 3 f and 3 g may be rolled with cathode foil 2 barranged at the position of cathode foil 2 a, cathode foil 2 a arrangedat the position of chemically processed anode foil 1 b, and chemicallyprocessed anode foil 1 b arranged at the position of cathode foil 2 b.Specifically, two chemically processed anode foils 1 a and 1 b, twocathode foils 2 a and 2 b and two separator sheets 3 f and 3 g may berolled with foils of different poles arranged along the direction ofrolling DR1.

In electrolytic capacitor 10A, each of capacitor elements 5 c and 5 d isformed of the chemically processed anode foil and the cathode foilhaving the length L and width W, and has capacitance C. Capacitorelement 5 has the same effect as attained by two capacitor elements 5 cand 5 d connected in parallel, and therefore, its capacitance is 2C(=C0), which is the same as the capacitance C0 of the conventionalaluminum rolled solid electrolytic capacitor 100.

Therefore, even though electrolytic capacitor 10A is fabricated by usingchemically processed anode foils 1 and cathode foils 2 having one-halfthe length of conventional chemically processed anode foil 110, thecapacitance is not smaller than the capacitance of the conventionalaluminum rolled solid electrolytic capacitor 100, while equivalentseries resistance becomes one-half that of the conventional aluminumrolled solid electrolytic capacitor 100.

Further, electrolytic capacitor 10A is formed by replacing conventionalchemically processed anode foil 110 and cathode foil 120 with twochemically processed anode foils and two cathode foils, and therefore,the diameter after rolling is approximately the same as that of theconventional aluminum rolled solid electrolytic capacitor 100. In otherwords, it is possible to form electrolytic capacitor 10A having reducedequivalent series resistance while maintaining the capacitance and notmaking the size larger than the conventional aluminum rolled solidelectrolytic capacitor 100.

FIG. 11 is a still another perspective view showing the structure of theelectrolytic capacitor in accordance with Embodiment 1 of the presentinvention. The electrolytic capacitor in accordance with Embodiment 1 ofthe present invention may be a electrolytic capacitor 10B shown in FIG.11. Referring to FIG. 11, electrolytic capacitor 10B is formed by addingan anode terminal 18 and a cathode terminal 19 to electrolytic capacitor10 shown in FIG. 1, and except for this point, it is the same aselectrolytic capacitor 10.

Anode terminal 18 is connected to two anode leads 11 and 12, and cathodeterminal 19 is connected to two cathode leads 13 and 14. In this manner,in electrolytic capacitor 10B, two anode leads 11 and 12 and two cathodeleads 13 and 14 are connected respectively to one anode terminal 18 andone cathode terminal 19. Therefore, electrolytic capacitor 10B is anelectrolytic capacitor having a 2-terminal structure.

It is noted that in electrolytic capacitor 10B, two anode leads 11 and12 and two cathode leads 13 and 14 may not be connected to one anodeterminal 18 and one cathode terminal 19, respectively, and they may bebundled together for use.

Further, in Embodiment 1, anode terminal 18 and cathode terminal 19 maybe added to electrolytic capacitor 10A.

FIG. 12 is a plan view of the chemically processed anode foils andcathode foils. Referring to FIG. 12, a chemically processed anode foil21 a and a cathode foil 22 a have the length L1 and width W, and achemically processed anode foil 21 b and a cathode foil 22 b have thelength L2 and width W. Here, L1+L2=2L.

In the present invention, chemically processed anode foils 1 a and 1 band cathode foils 2 a and 2 b of electrolytic capacitor 10 and 10A maybe replaced by chemically processed anode foils 21 a and 21 b andcathode foils 22 a and 22 b, respectively.

Here, capacitance of a capacitor element consisting of chemicallyprocessed anode foil 21 a, separator sheet 3 b and cathode foil 22 a isdifferent from that of a capacitor element consisting of chemicallyprocessed anode foil 21 b, separator sheet 3 d and cathode foil 22 b.

Therefore, in the present invention, two capacitor elements contained inelectrolytic capacitor 10 or 10A may have mutually differentcapacitances.

The method of setting capacitances of two capacitor elements containedin electrolytic capacitor 10 or 10A different from each other is notlimited to the method in which the length of chemically processed anodefoil and cathode foil in one capacitor element is set different from thelength of chemically processed anode foil and cathode foil in the othercapacitor element. A method in which the width of chemically processedanode foil and cathode foil in one capacitor element is set differentfrom the width of chemically processed anode foil and cathode foil inthe other capacitor element may be adopted.

Specifically, the method of setting capacitances of two capacitorelements contained in electrolytic capacitor 10 or 10A different fromeach other may be the method of setting the area of chemically processedanode foil and cathode foil in one capacitor element different from thearea of chemically processed anode foil and cathode foil in the othercapacitor element. In addition, a method of varying the foil type orvarying the voltage for chemically processing the foil may be adopted.

In the foregoing, the number of chemically processed anode foils andcathode foils has been described as two or three. In the presentinvention, the number is not limited to these, and generally, the numberof chemically processed anode foils and cathode foils may be n (n is aninteger not smaller than 2).

In this case, the number of separator sheets is set to 2n or 2n−1, andthe number of anode leads and the number of cathode leads are each setto n. Here, n anode leads may be connected to one anode terminal, and ncathode leads may be connected to one cathode terminal. When thediameter attained by rolling n chemically processed anode foils 1, ncathode foils 2 and 2n or 2n−1 separator sheets 3 is to be setapproximately the same as the diameter attained by rolling onechemically processed anode foil 110, one cathode foil 120 and twoseparator sheets 130, the length of each of n chemically processed anodefoils 1 and n cathode foils 2 is set to one-nth of the length ofchemically processed anode foil 110 and cathode foil 120 when onechemically processed anode foil 110, one cathode foil 120 and one or twoseparator sheets 130 are rolled.

When electrolytic capacitor 10 or 10A is fabricated by rolling nchemically processed anode foils 1, n cathode foils 2 and 2n or 2n−1separator sheets 3, electrolytic capacitor 10 or 10A comes to include ncapacitor elements. In the present invention, the capacitances of ncapacitor elements may be made different from each other through themethods described above.

In the foregoing, lead tab terminals 6 to 9 have been described asconnected to the position of L/2 from the rolling start end 1A ofchemically processed anode foils 1 a and 1 b and cathode foils 2 a and 2b. It is not limiting, and in the present invention, lead tab terminals6 to 9 may be connected to a position in the range of 7L/20 to 13L/20from the rolling start end 1A of chemically processed anode foils 1 aand 1 b and cathode foils 2 a and 2 b.

The reason for this is that, as long as lead tab terminals 6 to 9 areconnected to a position in the range of 7L/20 to 13L/20 from the rollingstart end 1A of chemically processed anode foils 1 a and 1 b and cathodefoils 2 a and 2 b, the equivalent series resistance of electrolyticcapacitor 10 or 10A is almost constant.

Further, though electrolytic capacitors 10 and 10A have been describedas containing solid electrolyte in the foregoing, the present inventionis not limited thereto and electrolytic capacitor 10 or 10A may includeliquid electrolyte. Specifically, electrolytic capacitor 10 and 10A haveonly to contain electrolyte, that is, either solid electrolyte or liquidelectrolyte.

Further, though chemically processed anode foil 1 and cathode foil 2have been described as formed of aluminum foil in the foregoing, thepresent invention is not limited thereto, and chemically processed anodefoil 1 and cathode foil 2 may be vapor-deposited foil of valve metaloxide, vapor-deposited foil of single metal nitride, vapor-depositedfoil of composite metal nitride, carbon foil or the like.

Further, electrolytic capacitor 10 or 10A in accordance with Embodiment1 of the present invention may be fabricated by using chemicallyprocessed anode foil 1 and cathode foil 2 having the same length as thatof chemically processed anode foil 110 and cathode foil 120 of aluminumrolled solid electrolytic capacitor 100. In that case, electrolyticcapacitor 10 comes to have a capacitance larger than that of aluminumrolled solid electrolytic capacitor 100 and the diameter larger thanthat of aluminum rolled solid electrolytic capacitor 100.

In the present invention, the aluminum rolled solid electrolyticcapacitor 100 fabricated by rolling one chemically processed anode foil110, one cathode foil 120 and one or two separator sheets 130 representsa “reference electrolytic capacitor.”

Embodiment 2

FIG. 13 is a perspective view showing a structure of an electrolyticcapacitor in accordance with Embodiment 2. Referring to FIG. 13, anelectrolytic capacitor 20 in accordance with Embodiment 2 is formed byreplacing two cathode foils 2 a and 2 b of electrolytic capacitor 10Ashown in FIGS. 8 and 10 by one cathode foil 23, and except for thispoint, it is the same as electrolytic capacitor 10A. Therefore,electrolytic capacitor 20 also includes two capacitor elements 5 c and 5d arranged at different positions along the radial direction. Inelectrolytic capacitor 20, resin seal may be used in place of rubberpacking 16. Further, resin seal may be used not only in electrolyticcapacitor 20 but also in electrolytic capacitors 10, 10A and 10B.

FIG. 14 is a plan view of a cathode foil 23 shown in FIG. 13. Referringto FIG. 14, cathode foil 23 has the length 2L and the width W. Lead tabterminal 8 is connected to cathode foil 23 at a position of a distanceL/2 from one end 23A of cathode foil 23, and lead tab terminal 9 isconnected to cathode foil 23 at a position of a distance L/2 from theother end 23B of cathode foil 23. As a result, the distance between leadtab terminals 8 and 9 is L.

FIG. 15 is a perspective view showing the method of arranging chemicallyprocessed anode foils 1 a, 1 b, cathode foil 23 and separator sheets 3 fand 3 g when electrolytic capacitor 20 shown in FIG. 13 is fabricated.Referring to FIG. 15, two chemically processed anode foils 1 a and 1 bare arranged continuously between separator sheets 3 f and 3 g. Here,two chemically processed anode foils 1 a and 1 b are arranged spaced bya prescribed distance to be electrically insulated from each other.Further, cathode foil 23 is arranged to be opposite to chemicallyprocessed anode foils 1 a and 1 b with separator sheet 3 g interposed.

Two chemically processed anode foils 1 a and 1 b, one cathode foil 23and two separator sheets 3 f and 3 g are arranged in the manner as shownin FIG. 15, and two chemically processed anode foils 1 a and 1 b, onecathode foil 23 and two separator sheets 3 f and 3 g are rolled fromrolling start ends 1A, 23A and 3A in the direction of rolling DR1,whereby capacitor element 5 including two capacitor elements 5 c and 5 dis formed. At the point where chemically processed anode foil 1 a,cathode foil 23 of the length L and separator sheets 3 f and 3 g of thelength L are rolled, capacitor element 5 c is formed, and at the pointwhere chemically processed anode foil 1 b, cathode foil 23 of theremaining length L and separator sheets 3 f and 3 g of the remaininglength L are rolled, capacitor element 5 d is formed.

Thus, capacitor element 5 c is arranged on the inner circumferentialside, and capacitor element 5 d is arranged on the outer circumferentialside.

In fabricating electrolytic capacitor 20, it is unnecessary that twochemically processed anode foils 1 a and 1 b, one cathode foil 23 andtwo separator sheets 3 f and 3 g are rolled from the rolling start ends1A, 23A and 3A, and two chemically processed anode foils 1 a and 1 b,one cathode foil 23 and two separator sheets 3 f and 3 g may be rolledfrom the central portion of two separator sheets 3 f and 3 g. Dependenton the manner of rolling two chemically processed anode foils 1 a and 1b, one cathode foil 23 and two separator sheets 3 f and 3 g, lead tabterminals 6 to 9 come to be arranged in a rectangle as shown in FIG. 1or arranged linearly as shown in FIG. 13.

After forming capacitor element 5 by rolling two chemically processedanode foils 1 a and 1 b, one cathode foil 23 and two separator sheets 3f and 3 g, electrolytic capacitor 20 is fabricated by the same method asthat of fabricating electrolytic capacitor 10. In fabricatingelectrolytic capacitor 20, by using resin seal in place of rubberpacking 16, production yield (throughput) can be improved, as the resinseal is easier to manufacture than rubber packing.

In electrolytic capacitor 20, each of capacitor elements 5 c and 5 d isformed by the chemically processed anode foil and the cathode foilhaving the length L and width W, and hence, it has the capacitance C.Capacitor element 5 has the same effect as attained by two capacitorelements 5 c and 5 d connected in parallel, and therefore, itscapacitance is 2C=(C0), which is the same as that of the conventionalaluminum rolled solid electrolytic capacitor 100.

Therefore, even though electrolytic capacitor 20 is fabricated usingchemically processed anode foil 1 having one-half the length of theconventional chemically formed anode 110 and cathode foil 23 having thesame length as the conventional cathode foil 120, its capacitance is notsmaller than that of conventional aluminum rolled solid electrolyticcapacitor 100, while its equivalent series resistance becomes one-halfthat of conventional aluminum rolled solid electrolytic capacitor 100.

Further, electrolytic capacitor 20 is fabricated by dividingconventional chemically processed anode foil 110 into two chemicallyprocessed anode foils 1 a and 1 b arranged continuously in the directionof rolling DR1, and therefore, the diameter after rolling isapproximately the same as that of conventional aluminum rolled solidelectrolytic capacitor 100. Specifically, electrolytic capacitor 20having reduced equivalent series resistance can be fabricated while thecapacitance is maintained and the size is not made larger than that ofconventional aluminum rolled solid electrolytic capacitor 100.

As described above, by using one cathode foil 23 and two chemicallyprocessed anode foils 1 a and 1 b, electrolytic capacitor 20 having thesame effect as attained by two capacitor elements 5 c and 5 d connectedin parallel can be fabricated.

Table 2 shows, in comparison, electric characteristics of electrolyticcapacitor 20 in accordance with Embodiment 2 and the conventionalelectrolytic capacitor.

TABLE 2 Leakage Sealing Capacitance tanδ ESR current Cathode foilmaterial (μF) (%) (mΩ) (μA) Conventional Aluminum Rubber 565 2.5 5.5 11Example 1 foil Example 1 Aluminum Rubber 567 2.3 2.7 12 foil Example 2Aluminum Resin 562 2.5 2.7 18 foil Conventional Aluminum Rubber 1520 1.87.0 13 Example 2 nitride film Example 3 Aluminum Rubber 1532 1.7 3.4 11nitride film Example 4 Aluminum Resin 1539 1.7 3.4 19 nitride film

Referring to Table 2, Conventional Examples 1 and 2 representelectrolytic capacitors consisting of only one capacitor element 150fabricated by using chemically processed anode foil 110 and cathode foil120 having the length L, and Example 1 represents electrolytic capacitor20 fabricated by using two chemically processed anode foils 1 a and 1 b,one cathode foil 23 and rubber packing 16.

Example 2 represents electrolytic capacitor 20 fabricated by using resinseal in place of rubber packing 16 of Example 1, and Example 3represents electrolytic capacitor 20 fabricated by replacing cathodefoil 23 of Example 1 by aluminum foil having a titanium aluminum nitridefilm formed thereon and using two chemically processed anode foil 1 aand 1 b and one cathode foil 23, and Example 4 represent electrolyticcapacitor 20 fabricated by replacing rubber packing 16 of Example 3 byresin seal.

Capacitance and dielectric tangent (tan δ) were measured at 120 Hz,equivalent series resistance ESR was measured at 100 kHz, and leakagecurrent LC is a value when rated voltage was applied for two minutes.

The titanium aluminum nitride film was formed by vapor deposition on thesurface of aluminum foil. Values of capacitance, dielectric tangent (tanδ) and equivalent series resistance ESR shown in Table 2 are averagevalues among 30 samples.

From the results shown in Table 2, the capacitance and dielectrictangent (tan δ) of electrolytic capacitor 20 in accordance withEmbodiment 2 are approximately the same as those of ConventionalExamples 1 and 2. It is noted that equivalent series resistance ESR ofelectrolytic capacitor 20 in accordance with Embodiment 2 is reduced toabout one-half that of Conventional Examples 1 and 2 (see Examples 1 to4). Further, equivalent series resistance ESR does not vary when rubberpacking 16 is replaced by resin seal.

It is confirmed through experiment that even when only one cathode foilis used, the equivalent series resistance can be reduced toapproximately one-half while the capacitor capacitance is maintained, byincreasing the number of chemically processed anode foils to two.Further, it is also confirmed through experiment that the equivalentseries resistance does not vary even when resin seal is used.

FIG. 16 is a perspective view showing another method of arranging thechemically processed anode foils, cathode foil and separator sheets whenthe electrolytic capacitor shown in FIG. 13 is fabricated by using twochemically processed anode foils and one cathode foil. Referring to FIG.16, when electrolytic capacitor 20 shown in FIG. 13 is formed by usingtwo chemically processed anode foils and one cathode foil, electrolyticcapacitor 20 includes a separator sheet 3 h in addition to two separatorsheets 3 f and 3 g.

Separator sheets 3 f and 3 g may be shorter than separator sheet 3 h, aslong as they are longer than chemically processed anode foils 1 a and 1b. Chemically processed anode foil 1 a is arranged between separatorsheets 3 g and 3 h, while chemically processed anode foil 1 b isarranged between separator sheets 3 f and 3 g. Here, chemicallyprocessed anode foil 1 b is arranged continuous to chemically processedanode foil 1 a in the direction of rolling DR1. Cathode foil 23 isarranged to be opposite to chemically processed anode foil 1 a withseparator sheet 3 h interposed, and opposite to chemically processedanode foil 1 b with separator sheets 3 g and 3 h interposed.

Two chemically processed anode foils 1 a and 1 b, one cathode foil 23and three separator sheets 3 f, 3 g and 3 h are arranged in the manneras shown in FIG. 16, and two chemically processed anode foils 1 a and 1b, one cathode foil 23 and three separator sheets 3 f, 3 g and 3 h arerolled from rolling start ends 1A, 23A and 3A in the direction ofrolling DR1, so that capacitor element 5 including two capacitorelements 5 c and 5 d is formed. At the point where chemically processedanode foil 1 a, cathode foil 23 of the length L and separator sheets 3f, 3 g and 3 h of the length L are rolled, capacitor element 5 c isformed, and at the point where chemically processed anode foil 1 b,cathode foil 23 of the remaining length L and separator sheets 3 f, 3 gand 3 h of the remaining length L are rolled, capacitor element 5 d isformed.

Therefore, capacitor element 5 c is arranged on the innercircumferential side, and capacitor element 5 d is arranged on the outercircumferential side.

After forming capacitor element 5 by rolling two chemically processedanode foils 1 a and 1 b, one cathode foil 23 and three separator sheets3 f, 3 g and 3 h, electrolytic capacitor 20 is fabricated by the samemethod as that of fabricating electrolytic capacitor 10.

Electrolytic capacitor 20 fabricated by using two chemically processedanode foils 1 a and 1 b, one cathode foil 23 and three separator sheets3 f, 3 g and 3 h includes, in addition to the example fabricated byusing two chemically processed anode foils 1 a and 1 b, one cathode foil23 and two separator sheets 3 f and 3 g, only one additional separatorsheet 3 h. Therefore, the diameter after rolling is approximately thesame as that of conventional aluminum rolled solid electrolyticcapacitor 100.

When electrolytic capacitor 20 is fabricated using two chemicallyprocessed anode foils 1 a and 1 b, one cathode foil 23 and threeseparator sheets 3 f, 3 g and 3 h, chemically processed anode foil 1 amay be arranged between separator sheets 3 f and 3 g, and chemicallyprocessed anode foil 1 b may be arranged between separator sheets 3 gand 3 h, in FIG. 16.

FIG. 17 is a perspective view showing a still another method ofarranging the chemically processed anode foils, cathode foil andseparator sheets when the electrolytic capacitor shown in FIG. 13 isfabricated by using two chemically processed anode foils and one cathodefoil.

Referring to FIG. 17, cathode foil 23 is arranged between separatorsheets 3 f and 3 g. Chemically processed anode foil 1 a is arranged tobe opposite to cathode foil 23 with separator sheet 3 g interposed, andchemically processed anode foil 1 b is arranged to be opposite tocathode foil 23 with separator sheet 3 f interposed. Here, chemicallyprocessed anode foil 1 b is arranged continuous to chemically processedanode foil 1 a in the direction of rolling DR1.

Two chemically processed anode foils 1 a and 1 b, one cathode foil 23and two separator sheets 3 f and 3 g are arranged in the manner as shownin FIG. 17, and two chemically processed anode foils 1 a and 1 b, onecathode foil 23 and two separator sheets 3 f and 3 g are rolled fromrolling start ends 1A, 23A and 3A in the direction of rolling DR1, sothat capacitor element 5 including two capacitor elements 5 c and 5 d isformed. At the point where chemically processed anode foil 1 a, cathodefoil 23 of the length L and separator sheets 3 f and 3 g of the length Lare rolled, capacitor element 5 c is formed, and at the point wherechemically processed anode foil 1 b, cathode foil 23 of the remaininglength L and separator sheets 3 f and 3 g of the remaining length L arerolled, capacitor element 5 d is formed.

Therefore, capacitor element 5 c is arranged on the innercircumferential side, and capacitor element 5 d is arranged on the outercircumferential side.

After forming capacitor element 5 by rolling two chemically processedanode foils 1 a and 1 b, one cathode foil 23 and two separator sheets 3f and 3 g, electrolytic capacitor 20 is fabricated by the same method asthat of fabricating electrolytic capacitor 10.

In fabricating electrolytic capacitor 20, it is unnecessary that twochemically processed anode foils 1 a and 1 b, one cathode foil 23 andtwo separator sheets 3 f and 3 g are rolled from the rolling start ends1A, 23A and 3A, and two chemically processed anode foils 1 a and 1 b,one cathode foil 23 and two separator sheets 3 f and 3 g may be rolledfrom the central portion of two separator sheets 3 f and 3 g. Dependenton the manner of rolling two chemically processed anode foils 1 a and 1b, one cathode foil 23 and two separator sheets 3 f and 3 g, lead tabterminals 6 to 9 come to be arranged in a rectangle as shown in FIG. 1or arranged linearly as shown in FIG. 13.

Further, when electrolytic capacitor 20 is fabricated by using twochemically processed anode foils 1 a and 1 b, one cathode foil 23 andtwo separator sheets 3 f and 3 g, chemically processed anode foil 1 amay be arranged to be opposite to cathode foil 23 with separator sheet 3f interposed, and chemically processed anode foil 1 b may be arranged tobe opposite to cathode foil 23 with separator sheet 3 g interposed, inFIG. 17.

FIG. 18 is another perspective view showing the structure of theelectrolytic capacitor in accordance with Embodiment 2. The electrolyticcapacitor in accordance with Embodiment 2 may be an electrolyticcapacitor 20A shown in FIG. 18. Referring to FIG. 18, electrolyticcapacitor 20A is formed by replacing chemically processed anode foils 1a and 1 b of electrolytic capacitor 20 shown in FIGS. 13 and 15 bychemically processed anode foils 24 a, 24 b and 24 c, and by adding leadtab terminals 15 and 17, an anode lead 16 and a cathode lead 18, andexcept for these points, it is the same as electrolytic capacitor 20. Itis also possible in electrolytic capacitor 20A to use resin seal inplace of rubber packing 16.

In electrolytic capacitor 20A, capacitor element 5 includes capacitorelements 5 e, 5 f and 5 g. Capacitor element 5 e is arranged on theinnermost circumferential side, capacitor element 5 f is arranged on theouter side of capacitor element 5 e, and capacitor element 5 g isarranged on the outermost circumferential side.

FIG. 19 is a plan view of chemically processed anode foils 24 a to 24 c,cathode foil 23 and the separator sheets 3 f and 3 g formingelectrolytic capacitor 20A shown in FIG. 18. Referring to FIG. 19, inelectrolytic capacitor 20A, lead tab terminal 8 is connected to cathodefoil 23 at a position of the distance L/3 from one end 23A of cathodefoil 23, lead tab terminal 17 is connected to cathode foil 23 at aposition of the distance L/3 from the other end 23B of cathode foil 23,and lead tab terminal 9 is connected to cathode foil 23 at a position ofthe distance 2L/3 from each of lead tab terminals 8 and 17.

Chemically processed anode foil 24 includes three chemically processedanode foils 24 a, 24 b and 24 c. Each of the three chemically processedanode foils 24 a, 24 b and 24 c is formed of aluminum foil having itssurface chemically processed. Each of the three chemically processedanode foils 24 a, 24 b and 24 c has the length of 2L/3 and the width W.Lead tab terminal 6 is connected to chemically processed anode foil 24 aat a position of the distance L/3 from one end 24A of chemicallyprocessed anode foil 24 a, lead tab terminal 7 is connected tochemically processed anode foil 24 b at a position of the distance L/3from one end 24B of chemically processed anode foil 24 b, and lead tabterminal 15 is connected to chemically processed anode foil 24 c at aposition of the distance L/3 from one end 24C of chemically processedanode foil 24 c.

In electrolytic capacitor 20A, capacitor element 5 e consists ofchemically processed anode foil 24 a, cathode foil 23 and separatorsheets 3 f and 3 g, capacitor element 5 f consists of chemicallyprocessed anode foil 24 b, cathode foil 23 and separator sheets 3 f and3 g, and capacitor element 5 g consists of chemically processed anodefoil 24 c, cathode foil 23 and separator sheets 3 f and 3 g.

FIG. 20 is a perspective view showing a method of arranging chemicallyprocessed anode foils 24 a, 24 b and 24 c, cathode foil 23 and separatorsheets 3 f and 3 g when electrolytic capacitor 20A shown in FIG. 18 isfabricated. Referring to FIG. 20, cathode foil 23 is arranged betweenseparator sheets 3 f and 3 g. Three chemically processed anode foils 24a, 24 b and 24 c are arranged to be opposite to cathode foil 23 withseparator sheet 3 g interposed. Specifically, three chemically processedanode foils 24 a, 24 b and 24 c are arranged continuously in thedirection of rolling DR1. Here, three chemically processed anode foils24 a, 24 b and 24 c are arranged spaced by a prescribed distance to beelectrically insulated from each other.

Three chemically processed anode foils 24 a, 24 b and 24 c, one cathodefoil 23 and two separator sheets 3 f and 3 g are arranged in the manneras shown in FIG. 20, and three chemically processed anode foils 24 a, 24b and 24 c, one cathode foil 23 and two separator sheets 3 f and 3 g arerolled form rolling start ends 3A, 23A and 24A in the direction ofrolling DR1, so that capacitor element 5 including three capacitorelements 5 e, 5 f and 5 g is formed. At the point where chemicallyprocessed anode foil 24 a, cathode foil 23 of the length 2L/3 andseparator sheets 3 f and 3 g of the length 2L/3 are rolled, capacitorelement 5 e is formed, at the point where chemically processed anodefoil 24 b, cathode foil 23 of the length 2L13 and separator sheets 3 fand 3 g of the length 2L/3 are rolled, capacitor element 5 f is formed,and at the point where chemically processed anode foil 24 c, cathodefoil 23 of the remaining length 2L/3 and separator sheets 3 f and 3 g ofthe remaining length 2L/3 are rolled, capacitor element 5 g is formed.

Therefore, capacitor element 5 e is arranged on the innermostcircumferential side, capacitor element 5 f is arranged on the outerside of capacitor element 5 e, and capacitor element 5 g is arranged onthe outermost circumferential side.

After forming capacitor element 5 by rolling three chemically processedanode foils 24 a, 24 b and 24 c, one cathode foil 23 and two separatorsheets 3 f and 3 g, electrolytic capacitor 20A is fabricated by the samemethod as that of fabricating electrolytic capacitor 10. When resin sealis used in place of rubber packing 16 for fabricating electrolyticcapacitor 20A, production yield (throughput) can be improved, as resinseal can be manufactured more easily than rubber packing 16.

In electrolytic capacitor 20A, each of capacitor elements 5 e, 5 f and 5g is formed by the chemically processed anode foil and the cathode foilhaving the length 2L/3 and the width W, and therefore, it has thecapacitance C1. Capacitor element 5 has the same effect as attained bythree capacitor elements 5 e, 5 f and 5 g connected in parallel, andtherefore, its capacitance is 3C1=(C0), which is the same as thecapacitance C0 of the conventional aluminum rolled solid electrolyticcapacitor 100.

Therefore, even though electrolytic capacitor 20A is fabricated usingchemically processed anode foils 24 a, 24 b and 24 c having one-thirdthe length of the conventional chemically formed anode 110 and cathodefoil 23 having the same length as the conventional cathode foil 120, itscapacitance is not smaller than that of conventional aluminum rolledsolid electrolytic capacitor 100, while its equivalent series resistancebecomes one-third that of conventional aluminum rolled solidelectrolytic capacitor 100.

Further, as electrolytic capacitor 20A is fabricated by dividingconventional chemically processed anode foil 110 into three chemicallyprocessed anode foils 24 a, 24 b and 24 c arranged continuously in thedirection of rolling DR1, the diameter after rolling is approximatelythe same as that of conventional aluminum rolled solid electrolyticcapacitor 100. Specifically, electrolytic capacitor 20A having reducedequivalent series resistance can be fabricated while the capacitance ismaintained and the size is not made larger than that of conventionalaluminum rolled solid electrolytic capacitor 100.

In this manner, by using one cathode foil 23 and three chemicallyprocessed anode foils 24 a, 24 b and 24 c, electrolytic capacitor 20Ahaving the same effect as attained by three capacitor elements 5 e, 5 fand 5 g connected in parallel can be fabricated.

FIG. 21 is a perspective view showing a method of arranging thechemically processed anode foils 24 a, 24 b and 24 c, cathode foil 23and separator sheets 3 f and 3 g when electrolytic capacitor 20A shownin FIG. 18 is fabricated by using three chemically processed anode foils24 a, 24 b and 24 c and one cathode foil 23.

Referring to FIG. 21, among the three chemically processed anode foils24 a, 24 b and 24 c, chemically processed anode foil 24 a is arranged tobe opposite to cathode foil 23 with separator sheet 3 f interposed. Themanner of arranging chemically processed anode foils 24 b and 24 c,cathode foil 23 and separator sheets 3 f and 3 g is the same as thatshown in FIG. 20. Here, three chemically processed anode foils 24 a, 24b and 24 c are arranged continuously in the direction of rolling DR1,and two chemically processed anode foils 24 b and 24 c are arrangedspaced by a prescribed distance to be electrically insulated from eachother.

Three chemically processed anode foils 24 a, 24 b and 24 c, one cathodefoil 23 and two separator sheets 3 f and 3 g are arranged in the manneras shown in FIG. 21, and three chemically processed anode foils 24 a, 24b and 24 c, one cathode foil 23 and two separator sheets 3 f and 3 g arerolled from rolling start ends 3A, 23A and 24A in the direction ofrolling DR1, so that capacitor element 5 including three capacitorelements 5 e, 5 f and 5 g is formed. At the point where chemicallyprocessed anode foil 24 a, cathode foil 23 of the length 2L/3 andseparator sheets 3 f and 3 g of the length 2L/3 are rolled, capacitorelement 5 e is formed, at the point where chemically processed anodefoil 24 b, cathode foil 23 of the length 2L/3 and separator sheets 3 fand 3 g of the length 2L/3 are rolled, capacitor element 5 f is formed,and at the point where chemically processed anode foil 24 c, cathodefoil 23 of the remaining length 2L/3 and separator sheets 3 f and 3 g ofthe remaining length 2L/3 are rolled, capacitor element 5 g is formed.

Therefore, capacitor element 5 e is arranged on the innermostcircumferential side, capacitor element 5 f is arranged on the outerside of capacitor element 5 e, and capacitor element 5 g is arranged onthe outermost circumferential side.

After forming capacitor element 5 by rolling three chemically processedanode foils 24 a, 24 b and 24 c, one cathode foil 23 and two separatorsheets 3 f and 3 g, electrolytic capacitor 20A is fabricated by the samemethod as that of fabricating electrolytic capacitor 10.

Though it has been described that among three chemically processed anodefoils 24 a, 24 b and 24 c, chemically processed anode foil 24 a isarranged to be opposite to cathode foil 23 with separator sheet 3 finterposed in the example of FIG. 21, the present invention is notlimited thereto, and among three chemically processed anode foils 24 a,24 b and 24 c, chemically processed anode foil 24 b or 24 c may bearranged to be opposite to cathode foil 23 with separator sheet 3 finterposed.

FIG. 22 is a perspective view showing another method of arrangingchemically processed anode foils 24 a, 24 b and 24 c, cathode foil 23and the separator sheets when electrolytic capacitor 20A shown in FIG.18 is fabricated by using three chemically processed anode foils 24 a,24 b and 24 c and one cathode foil 23.

Referring to FIG. 22, when electrolytic capacitor 20A shown in FIG. 18is formed by using three chemically processed anode foils 24 a, 24 b and24 c and one cathode foil 23, electrolytic capacitor 20A includesseparator sheets 3 h and 3 i in addition to two separator sheets 3 f and3 g.

Each of separator sheets 3 h and 3 i has the same length and same widthas separator sheets 3 f and 3 g. Chemically processed anode foil 24 a isarranged between separator sheets 3 g and 3 h to be opposite to cathodefoil 23 with separator sheet 3 g interposed, chemically processed anodefoil 24 b is arranged between separator sheets 3 h and 3 i to beopposite to cathode foil 23 with separator sheets 3 g and 3 hinterposed, and chemically processed anode foil 24 c is arranged to beopposite to cathode foil 23 with separator sheets 3 g, 3 h and 3 iinterposed. In this case, chemically processed anode foils 24 a, 24 band 24 c are arranged continuously in the direction of rolling DR1.

Three chemically processed anode foils 24 a, 24 b and 24 c, one cathodefoil 23 and four separator sheets 3 f, 3 g, 3 h and 3 i are arranged inthe manner as shown in FIG. 22, and three chemically processed anodefoils 24 a, 24 b and 24 c, one cathode foil 23 and four separator sheets3 f, 3 g, 3 h and 3 i are rolled from rolling start ends 3A, 23A and 24Ain the direction of rolling DR1, so that capacitor element 5 includingthree capacitor elements 5 e, 5 f and 5 g is formed. At the point wherechemically processed anode foil 24 a, cathode foil 23 of the length 2L/3and separator sheets 3 f, 3 g, 3 h and 3 i of the length 2L/3 arerolled, capacitor element 5 e is formed, at the point where chemicallyprocessed anode foil 24 b, cathode foil 23 of the length 2L/3 andseparator sheets 3 f, 3 g, 3 h and 3 i of the length 2L/3 are rolled,capacitor element 5 f is formed, and at the point where chemicallyprocessed anode foil 24 c, cathode foil 23 of the remaining length 2L/3and separator sheets 3 f, 3 g, 3 h and 3 i of the remaining length 2L/3are rolled, capacitor element 5 g is formed.

Therefore, capacitor element 5 e is arranged on the innermostcircumferential side, capacitor element 5 f is arranged on the outerside of capacitor element 5 e, and capacitor element 5 g is arranged onthe outermost circumferential side.

After forming capacitor element 5 by rolling three chemically processedanode foils 24 a, 24 b and 24 c, one cathode foil 23 and four separatorsheets 3 f, 3 g, 3 h and 3 i, electrolytic capacitor 20A is fabricatedby the same method as that of fabricating electrolytic capacitor 10.

FIG. 23 is a still further perspective view showing the structure of theelectrolytic capacitor in accordance with Embodiment 2. The electrolyticcapacitor in accordance with Embodiment 2 may be an electrolyticcapacitor 20B shown in FIG. 23.

Referring to FIG. 23, electrolytic capacitor 20B is formed by replacingcathode foil 23 of electrolytic capacitor 20A shown in FIG. 18 bycathode foils 2 a and 2 b, and except for this point, it is the same aselectrolytic capacitor 20A. In electrolytic capacitor 20B, again, resinseal may be used in place of rubber packing 16.

FIG. 24 is a plan view of chemically processed anode foils 24 a to 24 c,cathode foils 2 a and 2 b and separator sheets 3 f and 3 g forming theelectrolytic capacitor shown in FIG. 23. Referring to FIG. 24, inelectrolytic capacitor 20B, lead tab terminal 8 is connected to cathodefoil 2 a at a position of the distance L/2 from one end 2A of cathodefoil 2 a, lead tab terminal 9 is connected to the other end 2B ofcathode foil 2 a, and lead tab terminal 17 is connected to cathode foil2 b at a position of the distance L/2 from the other end 2D of cathodefoil 2 b.

In electrolytic capacitor 20B, capacitor element 5 e consists ofchemically processed anode foil 24 a, cathode foil 2 a and separatorsheets 3 f and 3 g, capacitor element 5 f consists of chemicallyprocessed anode foil 24 b, cathode foils 2 a and 2 b and separatorsheets 3 f and 3 g, and capacitor element 5 g consists of chemicallyprocessed anode foil 24 c, cathode foil 2 b and separator sheets 3 f and3 g.

FIG. 25 is a perspective view showing a method of arranging chemicallyprocessed anode foils 24 a, 24 b and 24 c, cathode foils 2 a and 2 b andseparator sheets 3 f and 3 g when the electrolytic capacitor 20B shownin FIG. 23 is fabricated. Referring to FIG. 25, cathode foils 2 a and 2b are arranged between separator sheets 3 f and 3 g. Three chemicallyprocessed anode foils 24 a, 24 b and 24 c are arranged to be opposite tocathode foils 2 a and 2 b with separator sheet 3 g interposed.Specifically, three chemically processed anode foils 24 a, 24 b and 24 care arranged continuously in the direction of rolling DR1. Here, threechemically processed anode foils 24 a, 24 b and 24 c are arranged spacedby a prescribed distance to be electrically insulated from each other,and two cathode foils 2 a and 2 b are arranged spaced by a prescribeddistance to be electrically insulated from each other.

Three chemically processed anode foils 24 a, 24 b and 24 c, two cathodefoils 2 a and 2 b, and two separator sheets 3 f and 3 g are arranged inthe manner as shown in FIG. 25, and three chemically processed anodefoils 24 a, 24 b and 24 c, two cathode foils 2 a and 2 b, and twoseparator sheets 3 f and 3 g are rolled from rolling start ends 2A, 3Aand 24A in the direction of rolling DR1, so that capacitor element 5including three capacitor elements 5 e, 5 f and 5 g is formed. At thepoint where chemically processed anode foil 24 a, cathode foil 2 a ofthe length 2L/3 and separator sheets 3 f and 3 g of the length 2L/3 arerolled, capacitor element 5 e is formed, at the point where chemicallyprocessed anode foil 24 b, cathode foil 2 a of the length L/3, cathodefoil 2 b of the length L/3 and separator sheets 3 f and 3 g of thelength 2L/3 are rolled, capacitor element 5 f is formed, and at thepoint where chemically processed anode foil 24 c, cathode foil 2 b ofthe remaining length 2L/3 and separator sheets 3 f and 3 g of theremaining length 2L/3 are rolled, capacitor element 5 g is formed.

Therefore, capacitor element 5 e is arranged on the innermostcircumferential side, capacitor element 5 f is arranged on the outerside of capacitor element 5 e, and capacitor element 5 g is arranged onthe outermost circumferential side.

After forming capacitor element 5 by rolling three chemically processedanode foils 24 a, 24 b and 24 c, two cathode foils 2 a and 2 b and twoseparator sheets 3 f and 3 g, electrolytic capacitor 20B is fabricatedby the same method as that of fabricating electrolytic capacitor 10.When resin seal is used in place of rubber packing 16 for fabricatingelectrolytic capacitor 20B, production yield (throughput) can beimproved, as resin seal can be manufactured more easily than rubberpacking 16.

In fabricating electrolytic capacitor 20B, it is unnecessary that threechemically processed anode foils 24 a, 24 b and 24 c, two cathode foil 2a and 2 b and two separator sheets 3 f and 3 g are rolled from therolling start ends 2A, 3A and 24A, and three chemically processed anodefoils 24 a, 24 b and 24 c, two cathode foil 2 a and 2 b and twoseparator sheets 3 f and 3 g may be rolled from the central portion oftwo separator sheets 3 f and 3 g. Dependent on the manner of rollingthree chemically processed anode foils 24 a, 24 b and 24 c, two cathodefoil 2 a and 2 b and two separator sheets 3 f and 3 g, lead tabterminals 6 to 9, 15 and 17 come to be arranged linearly as shown inFIG. 23 or arranged in a different shape.

In electrolytic capacitor 20B, each of capacitor elements 5 e, 5 f and 5g is formed by the chemically processed anode foil and the cathode foilhaving the length 2L/3 and the width W, and therefore, it has thecapacitance C1. Capacitor element 5 has the same effect as attained bythree capacitor elements 5 e, 5 f and 5 g connected in parallel, andtherefore, its capacitance is 3C1=(C0), which is the same as thecapacitance C0 of the conventional aluminum rolled solid electrolyticcapacitor 100.

Therefore, even though electrolytic capacitor 20B is fabricated usingchemically processed anode foils 24 a, 24 b and 24 c having one-thirdthe length of the conventional chemically formed anode 110 and cathodefoils 2 a and 2 b having one-half the length of the conventional cathodefoil 120, its capacitance is not smaller than that of conventionalaluminum rolled solid electrolytic capacitor 100, while its equivalentseries resistance becomes one-third that of conventional aluminum rolledsolid electrolytic capacitor 100.

Further, as electrolytic capacitor 20B is fabricated by dividingconventional chemically processed anode foil 110 into three chemicallyprocessed anode foils 24 a, 24 b and 24 c arranged continuously in thedirection of rolling DR1 and dividing conventional cathode foil 120 intotwo cathode foils 2 a and 2 b arranged continuously in the direction ofrolling DR1, the diameter after rolling is approximately the same asthat of conventional aluminum rolled solid electrolytic capacitor 100.Specifically, electrolytic capacitor 20B having reduced equivalentseries resistance can be fabricated while the capacitance is maintainedand the size is not made larger than that of conventional aluminumrolled solid electrolytic capacitor 100.

In this manner, by using two cathode foils 2 a and 2 b and threechemically processed anode foils 24 a, 24 b and 24 c, electrolyticcapacitor 20B having the same effect as attained by three capacitorelements 5 e, 5 f and 5 g connected in parallel can be fabricated.

FIG. 26 is a perspective view showing a method of arranging chemicallyprocessed anode foils 24 a, 24 b and 24 c, cathode foils 2 a and 2 b andthe separator sheets when electrolytic capacitor 20B shown in FIG. 23 isfabricated by using three chemically processed anode foils 24 a, 24 band 24 c and two cathode foils 2 a and 2 b.

Referring to FIG. 26, when electrolytic capacitor 20B shown in FIG. 23is formed by using three chemically processed anode foils 24 a, 24 b and24 c and two cathode foils 2 a and 2 b, electrolytic capacitor 20Bincludes a separator sheet 3 h in addition to two separator sheets 3 fand 3 g.

Separator sheets 3 f and 3 g may be shorter than separator sheet 3 h, aslong as they are longer than cathode foils 2 a and 2 b. Cathode foil 2 ais arranged between separator sheets 3 and 3 h to be opposite tochemically processed anode foils 24 a and 24 b with separator sheet 3 hinterposed, and cathode foil 2 b is arranged between separator sheets 3f and 3 g to be opposite to chemically processed anode foils 24 b and 24c with separator sheets 3 g and 3 h interposed.

Three chemically processed anode foils 24 a, 24 b and 24 c, two cathodefoils 2 a and 2 b, and three separator sheets 3 f, 3 g and 3 h arearranged in the manner as shown in FIG. 26, and three chemicallyprocessed anode foils 24 a, 24 b and 24 c, two cathode foils 2 a and 2b, and three separator sheets 3 f, 3 g and 3 h are rolled from rollingstart ends 2A, 3A and 24A in the direction of rolling DR1, so thatcapacitor element 5 including three capacitor elements 5 e, 5 f and 5 gis formed. At the point where chemically processed anode foil 24 a,cathode foil 2 a of the length 2L/3 and separator sheets 3 f, 3 g and 3h of the length 2L/3 are rolled, capacitor element 5 e is formed, at thepoint where chemically processed anode foil 24 b, cathode foil 2 a ofthe length L/3, cathode foil 2 b of the length L/3 and separator sheets3 f, 3 g and 3 h of the length 2L/3 are rolled, capacitor element 5 f isformed, and at the point where chemically processed anode foil 24 c,cathode foil 2 b of the remaining length 2L/3 and separator sheets 3 f,3 g and 3 h of the remaining length 2L/3 are rolled, capacitor element 5g is formed.

Therefore, capacitor element 5 e is arranged on the innermostcircumferential side, capacitor element 5 f is arranged on the outerside of capacitor element 5 e, and capacitor element 5 g is arranged onthe outermost circumferential side.

After forming capacitor element 5 by rolling three chemically processedanode foils 24 a, 24 b and 24 c, two cathode foils 2 a and 2 b and threeseparator sheets 3 f, 3 g and 3 h, electrolytic capacitor 20B isfabricated by the same method as that of fabricating electrolyticcapacitor 10.

In FIG. 26, cathode foil 2 a may be arranged between separator sheets 3f and 3 g to be opposite to chemically processed anode foils 24 a and 24b with separator sheets 3 g and 3 h interposed, and cathode foil 2 b maybe arranged between separator sheets 3 g and 3 h to be opposite tochemically processed anode foils 24 b and 24 c with separator sheet 3 hinterposed.

Further, in FIGS. 25 and 26, three chemically processed anode foils 24a, 24 b and 24 c may be arranged in the manner as shown in FIG. 22. Inthat case, electrolytic capacitor 20B comes to include additional oneseparator sheet 3 h or two separator sheets 3 h and 3 i.

In electrolytic capacitor 20B, lead tab terminal 9 may be arranged onone end 2C of cathode foil 2 b.

Except for this point, it is the same as Embodiment 1.

In Embodiment 2 above, an example in which an electrolytic capacitor isfabricated by using two chemically processed anode foils and one cathodefoil, an example in which an electrolytic capacitor is fabricated byusing three chemically processed anode foils and one cathode foil, andan example in which an electrolytic capacitor is fabricated by usingthree chemically processed anode foils and two cathode foils have beendescribed.

The present invention is not limited to these examples, and theelectrolytic capacitor in accordance with Embodiment 2 generallyencompasses an electrolytic capacitor fabricated by using i (i is aninteger not smaller than 2) chemically processed anode foils and j (j isan integer satisfying 1≦j<i) cathode foils, that is, smaller in numberthan i chemically processed anode foils.

In Embodiment 1 above, examples in which electrolytic capacitor isfabricated by using two or more, same number of chemically processedanode foils and cathode foils have been described, and in Embodiment 2,examples in which electrolytic capacitor is fabricated by using aplurality of chemically processed anode foils and one or more cathodefoils smaller in number than the plurality of chemically processed anodefoils have been described.

Therefore, the electrolytic capacitor in accordance with the presentinvention generally encompasses an electrolytic capacitor fabricated byusing i chemically processed anode foils, j (j is an integer satisfying1≦j≦i) cathode foils and k (k is an integer not smaller than 2)separator sheets. Here, i chemically processed anode foils areelectrically insulated from each other, and j cathode foils areelectrically insulated from each other when j is 2 or larger.

The embodiments as have been described here are mere examples and shouldnot be interpreted as restrictive. The scope of the present invention isdetermined by each of the claims with appropriate consideration of thewritten description of the embodiments and embraces modifications withinthe meaning of, and equivalent to, the languages in the claims.

1. A rolled electrolytic capacitor including an electrolyte, comprising:i (i is an integer not smaller than 2) anode members electricallyinsulated from each other and each having a dielectric coating film on asurface; j (j is an integer satisfying 1≦j<i) cathode members rolledtogether with said i anode members; and k (k is an integer not smallerthan 2) separator members arranged at least between said i anode membersand said j cathode members, and rolled together with said i anodemembers and said j cathode members, wherein at least two anode membersare initially stacked with respect to one another.
 2. A rolledelectrolytic capacitor including an electrolyte, comprising: i (i is aninteger not smaller than 2) anode members electrically insulated fromeach other and each having a dielectric coating film on a surface; icathode members rolled together with said i anode members; and k (k isan integer not smaller than 2) separator members each arranged betweenadjacent anode member and cathode member, and rolled together with saidi anode members and i cathode members; wherein a diameter attained whensaid i anode members, said i cathode members and said k separatormembers are rolled is approximately the same as a diameter of areference electrolytic capacitor having one anode member and one cathodemember rolled with one or two separator members interposed, and whereinat least two anode members are initially stacked with respect to oneanother.
 3. The electrolytic capacitor according to claim 2, whereinsaid i anode members, said i cathode members and said k separatormembers include n (n is an integer not smaller than 2) anode members, ncathode members and 2n or 2n−1 separator members; and each of said anodemembers, cathode members and separator members has approximately a 1/nlength of said anode member, said cathode member and said separatormember of said reference electrolytic capacitor.
 4. The electrolyticcapacitor according to claim 1, wherein a diameter attained when said ianode members, said j cathode members and said k separator members arerolled is approximately the same as a diameter of a referenceelectrolytic capacitor having one anode member and one cathode memberrolled with one or two separator members interposed.
 5. The electrolyticcapacitor according to claim 1, wherein said i anode members and said jcathode members respectively include n (n is an integer not smaller than2) anode members and m (m is an integer satisfying 1≦m<n) cathodemembers; a length of said anode member is approximately a 1/n length ofsaid anode member in said reference electrolytic capacitor; and lengthof said cathode member is approximately a 1/m length of said cathodemember in said reference electrolytic capacitor.
 6. The electrolyticcapacitor according to claim 5, wherein said m cathode members includeone cathode member.
 7. The electrolytic capacitor according to claim 1,wherein said i anode members, said j cathode members and said kseparator members form a plurality of capacitors having mutuallydifferent capacitances.
 8. The electrolytic capacitor according to claim1, further comprising a sealing member for sealing a capacitor elementformed by rolling said i anode members, said j cathode members and saidk separator members; wherein said sealing member is formed of resin. 9.The electrolytic capacitor according to claim 1, further comprising asealing member for sealing a capacitor element formed by rolling said ianode members, said j cathode members and said k separator members;wherein said sealing member is formed of rubber.
 10. The electrolyticcapacitor according to claim 1, wherein said electrolyte is solidelectrolyte formed of polythiophene-group, polypyrrole-group orpolyaniline-group conductive polymer or solid electrolyte of 7, 7, 8,8-tetracyano-quinodimethane complex salt.
 11. The electrolytic capacitoraccording to claim 2, wherein said electrolyte is solid electrolyteformed of polythiophene-group, polypyrrole-group or polyaniline-groupconductive polymer or solid electrolyte of 7, 7, 8,8-tetracyano-quinodimethane complex salt.
 12. The electrolytic capacitoraccording to claim 1, further comprising: a sealing member for sealing acapacitor element formed by rolling said i anode members, said j cathodemembers having a numerical equivalent of said i anode members, and saidk separator members; wherein said sealing member is formed of resin. 13.The electrolytic capacitor according to claim 1, further comprising: asealing member for sealing a capacitor element formed by rolling said ianode members, said j cathode members having a numerical equivalent ofsaid i anode members, and said k separator members, wherein said sealingmember is formed of rubber.